1. Field of the Invention
This invention relates to a process for producing a styrene-based polymer, and more particularly it relates to a process for producing a styrene-based polymer in which the stereochemical structure of the polymer chain comprises a syndiotactic configuration with good efficiency.
2. Description of Related Arts
A styrene-based polymer produced by the radical polymerization method has an atactic configuration in its stereochemical structure. It is molded into various shapes by various molding methods such as injection molding, extrusion molding, blow molding, vacuum molding and cast molding, and has been widely used for domestic electric appliances, office appliances, household goods, packaging containers, toys, furnitures, synthetic papers and other industrial materials.
However, a styrene-based polymer having atactic configuration has problems that it is inferior in heat resistance and chemical resistance.
The present inventors have previously developed a styrene-based polymer with high syndiotacticity, and it is further shown in Japanese Patent Application Laid-Open No. 187708/1987 that a styrene-based polymer having syndiotactic configuration can be obtained by using a two-component system catalyst comprising (A) a titanium compound and (B) a reaction product (an alkylaluminoxane) of an organic aluminum compound and a condensing agent.
However, the activity of the above catalyst is not sufficiently high and in particular it involves the problem that the cost of the catalyst is high because expensive alkylaluminoxane is used.